Have an Old Citation 12, still working fine - powers some LA Loudspeakers in my exercise room.

Have seen an ad for Bender ULT rebuild Kits, also a Nelson Pass FET Citation 12 article [found some info on your forum on this but it didn't answer my specific questions].

Any experiences with either of these rebuilds? Am curious about expenses on the Pass Plans, level of difficulty on completing the projects and the sonic signatures / general quality of the end product.

I am not familiar with the Bender, but the Pass circuit was
designed for minimal alteration of the existing hardware, and
used the same PC boards, and so on. It's a distinct improvement
over the original, but hardly a state of the art piece.